Electrical heating unit.



F. E. SHMLOR.

ELECTRICAL HEATING UNIT.

APPucATIoN man ocr.25. 1913.

Patented July 18, 1916.

, STATES PATENT omen.

FRANK E. vBHAIIBy-Ol DETROIT, MICHIGAN, ASSIGNOB T0 FRANK KUHN, 0IDETROIT, MICHIGAN.

nLncTarcaL HEATING UNIT.

specmuon of man Patent.

Patented July 18, 1916.

Application led October 25, 1913. Serialio. 797,188.

To all whom it may concern:

Be it known that I, FRaNx E. SHArnon, a citizen of the United States ofAmerlca, residing at Detroit, in the county'of Wayne and State ofMichigan, have invented certain new and useful Improvements inElectrical Heating Units, of which the follow- -mg 1s a specification,reference being had therein to. the accompanyin drawings.

The invention-relates to e ectrlcal heating units of that type in whichthe resistor isinsulated and armored.

vMore specifically, the invention relates to that cla in which theresistor is distributed in a lane, with the armor arranged in a para elplane.

It is the object 'of the invention to facilitate the conduction of theheat from the resistor into the armor. Further to increase the radiationfrom the armor, and further toA otherwise improve the construction as..hereinafter set forth.

. In the drawings: Figure 1 is a perspective view of 4an electricalheating unit con- 25 structed in. accordance with my invention; and Fig.2 is a cross section.

It is usual in the construction of heating units of the type abovedescribed to insulate the resistor by sheets of fiat insulatin material,such as mica, over which is lai a dat armor plate clamped to theresistor at the margin and at intermediate points.

It is an object tol obtain the best heat conduction between the resistorandI the armor,

by holdingall'portionsof the inner surface of the latter in iirm contactwiththe insulation vwhich separates it from the resistor. In ractice,however, such an effect is not obtamedfor the reason that the surface ofthe armor is never exactly parallel to the surface' of the insulationand only f contacts with the latter at points distributed over its area.Furthermore, the differential expansion of the insulating material `andthe metal will cause-more or less buckling and increase the `separationtherebetween. In addition to lack of contact the dissipation of heatfrom the armor is limited by theextent of its exposed surfacev whichbeing a plane, is the ,minimum within fixed dimensions.

y With my improved construction better heat conduction and increasedradiation is obtained' by substituting for the planearmor a roughenedsurface. This, while theoretically decreasing the surface contact withthe insulation, practically increases such contact by providing a largernumber of points of bearing. The roughened surface 1s also of greaterarea than a plane surface 60 so that the radiation is increased, while amore pleasing appearance is produced, especia ly after the surface ofthe armor becomes corroded-ithan with the plane armor.

In specific construction, A is a flat unit '65 of an desired shape ordimensions and provid with the usual terminal contacts B and B'.

yC is the resistor.

D and D are insulating sheets covering the opposite faces of theresistor, and E and E the armor plates These armor plates are formed ofToughened metal, preferably by forming indentations inpits surface asindicated in Fig. 2. The plates E and E 75. are clamped in position bysuitable means such as turn' over a marginal flange Fv and by intermeiate tie connections G. Thus the various points in the surface will beclamped agamst and tol a rlimited extent embedded in the insulation toproduce good heat conduction, while the Aincreased area of the outersurface will correspondingly inv crease the radiation.

What I claim as my invention is:

1. An electrical heating unit comprising a resistor havin an extendedflat surface, flat insulating eets disposed on opposite sides of saidresistor, and an armor plate consisting of `relatively thin corru tedmetal sheets clampedto the exposed si es of ythe insulating sheets.

2. In an electrical heating unit consistin of a resistor, atin'sulatingsheets dispo on opposite sides of said resistor, 'and' an 95 armor plateconsisting of corrugated sheets cliiped to the opposite sides of theinsula sheets, the contacting parts of said corrugated sheet inst theinsulating sheets bein embed ed in said insulating sheetsI the yincreasing the heat conduction of the heater.

In testimon whereof I aiiix my signature in presence o two witnesses.

v FRANK E. SHAILOR.

Witnesses:

H. W. Loren,

